The number of times I've cracked an egg into the sink then merrily thrown the shells into the mixer. As they are flying into the batter, I always think 'noooooo!!' but I'm too slow to turn it off in time.Lol, gravy cake!
As annoying and rude as that is (ugh, sisters!) she might be doing it with love though, thinking that you are getting more business and she is helping offset the difference by coming,and she gets to look good too. She probably doesn't realise how unhelpful her help would be. Doesn't make it right, but she probably loves ya!
http://www.flickr.com/photos/cakesdusoleil/2492548167/Not quite on topic, I was looking for tutorials and couldn't find anything but I found this, such a realistic cup and saucer, thought I'd post it's just so fab. Enjoy.
How about baking one in a cup and covering with fondant like a mini-half ball pan, do the colour, stiffened gumpaste handle, coloured fondant on the top like coffee, a couple of steam swirls, put on either a well stiffened gumpaste saucer, could dry over a real saucer, maybe that would work if stiff and thick enough? glue on and there ya go? Maybe do something like those cupcakes that have the hole in the middle where you scoop a little bit out in the middle and put in...
Kids craft: iron grated crayon between a folded piece and make butterflies.If it's the stuff I'm thinking of, make your own piping bags.Roll pastry or sticky cookies between then cut. Cleaner than smoodging on your bench.Only semi related...I found a great use for that lunch paper, the thin stuff that you get in huge rolls...put it on the kids easle, or just hang from a bar above a wall, keeps them painting for hours and much cheaper than anything else.